Rotatable couplings for coupling first and second sections of a core element are old and well-known in the push-pull art. Among these couplings are the ball and socket coupling, and the slug or enlargement coupling wherein a slug is attached to a core element to prevent the core element from being pulled through a hole small relative to the slug. U.S. Pat. No. 2,257,852 to Nicol and 2,899,836 to Cushman et al. teach rotatable couplings where a male section of core element is matingly engaged in a female section. Axial rotation can occur, but the two sections are locked against any axial sliding once coupled. This can be very important in particular applications where the core element must be maintained in a particular state of tension or compression.
While these two prior art assemblies solve a number of problems, they leave some problems unsolved. First, in both cases the design is not as efficient or compact as it could be. The U.S. Pat. No. 2,899,836 teaches the use of several separate parts. The U.S. Pat. No. 2,257,852 includes fewer parts to maintain the coupling, but because it includes a locking pin that extends through both the male and female sections of the core element, the coupling is not as compact as it could be. This could present problems where the environment calls for a very compact coupling. Also, both of the prior art couplings involve more effort to assemble than is necessary. This effort could translate into increased time and cost for assembly.
Prior art patents such as U.S. Pat. Nos. 4,645,245 to Cunningham and 4,111,464 to Asano et al. teach Quick Connect couplings for hoses, but these couplings do not prevent axial sliding between the connected elements, nor do they suggest that the couplings can be rotatable. Rubber "O" rings typically used in these couplings prevent or inhibit relative rotation between the male and female coupled members.